This invention relates to channeled glass articles such as neon or fluorescent lamps. More specifically, the glass articles are compact discharge lamps which can have the shape of conventional light bulbs.
Neon lighting devices are disclosed in U.S. Pat. No. 4,584,501 (Cocks et al.), U.S. Pat. No. 4,990,826 (Cocks et al.) and U.S. Pat. No. 5,036,243 (Cocks et al.). Generally, these patents disclose multifaceted lighting devices comprising glass or other vitreous plates which are hermetically sealed together to form a device with internally enclosed channels. These channels are thereafter evacuated and backfilled with an inert gas such as neon and thereafter ionized through the provision of a series of electrodes.
Generally, the method for forming the glass component of these prior art neon lighting devices involves cutting channels in a bottom glass plate followed by hermetically sealing a glass top plate to this channeled glass bottom plate. Various methods are used to cut the channels into the bottom glass plate including grinding, etching and sandblasting through an adhesive rubberized mask exhibiting a pattern identical in shape to the desired channel pattern.
In the past, many attempts have been made to produce fluorescent light envelopes that look like conventional light bulbs rather than the commonly found fluorescent tubes. These attempts merely resulted in bent tubes inside spherical, bulbous translucent envelopes with conventional incandescent bulb base caps. The bent tube, screw-in replacements for standard incandescent lamps were not very efficient and did not lend themselves to high-speed mass production.
Other attempts at producing spherical-bulb fluorescent lamps tried to avoid sealing the channels. However, when the channels are not sealed, cross communication between adjacent discharge paths occurs leading to undesirable effects. Attempts to prevent the arc from taking shortcut paths have had little success. To avoid this problem, one suggested solution makes the gap between the glass halves of the channel very small to increase resistance along the secondary path. This forces the arc discharge to follow the main current path along the channel. Another solution fills the gap with glass fibers or glass wool. Still another solution attempts to prevent cross talk by designing the ratio of the short path length to the ordinary discharge path length within certain ranges. Yet another attempt forms an evacuable envelope including inner and outer glass members of tapered cylindrical shape in nested coaxial relationship.
Briefly, the invention relates to a compact fluorescent lamp whose exterior and interior surfaces are defined by the front and back surfaces respectively, of a transparent envelope. One key aspect of the inventive lamp is that envelope has the shape of a conventional light bulb. The interior surface of the lamp defines a cavity whose walls (the interior surface of the lamp), is coated with phosphor. The transparent envelope is preferably made from glass and transparent glass-ceramic materials.
In another aspect, the interior surface includes at least one gas discharge channel capable of receiving a discharge or an ionizable gas, and at least two electrodes in communication with the channel. Preferably, the electrodes are located at opposite ends of the gas discharge channel and serve to generate an arc discharge when activated. A ballast housed in the cavity is also in electrical contact with the electrodes. When completely assembled, the envelope is secured to a screw-in base which is in electrical contact with the ballast.
In one aspect, this invention provides curved surfaces with formed, imbedded channels to replace the bent tubing commonly found in existing fluorescent lamps. This is done by forming sheets of glass that can be vacuum formed and/or pressed into the curved surfaces with integral channels. The process allows significant design flexibility for the lamp makers, including complex variations in the shape of the curved surface; the channel width and depth; and the general design of the channel path. The curved surface can be smooth with channels on one side, or part of the channel can be incorporated into both surfaces.
The inventive glass substrate for a compact fluorescent lamp can be made by several methods. For example (1) a glass or glass-ceramic substrate can be formed into a dome shape with the electronics and screw base nestled in the cavity formed by the dome; (2) the substrate can be formed into a shape which includes a neck that can be connected to a screw base; or (3) the substrate can be made from several parts which can be joined to enclose the ballast and electronics. The above options are not mutually exclusive, and may be combined several ways in a single lamp type.